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Big Freeze Discussion [Happy New Year]
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Weathercheck wrote: »Here is my thoughts with regard to snow risk.
Tuesday 1500hrs to Wednesday 2100hrs only.
http://img707.imageshack.us/img707/4500/risksnow.gif
did you put the line on the wrong side of trim by mistake :rolleyes:0 -
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Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 17,807 Mod ✭✭✭✭
Join Date:Posts: 17580
Weathercheck wrote: »Abit of surprise activity forming in the north irish sea alright.
Some decent shower could head into louth area pushing southeast off the south coast of NI
http://sat24.com/gb
I'd say these are your showers WC - not mine!
I see M2 bouy is back to E wind but IOM has a N wind.0 -
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Weathercheck wrote: »There is a line that isn't on the radar that is developing on the satellite, will be interesting to see if this develops into precip.
Yea appeared:
Then died out on next radar image:0 -
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Afternoon Everyone.
Great to see such interest in the weather on here
Brief Overview
Well, a split set of 12Z Model Guidance this afternoon into the medium term.
GFS, UKMO & GME redevelop an increasingly strong Easterly flow towards the end of the coming week. Meanwhile, the 12Z ECMWF has a rather slack flow at first, but still very cold, with a slightly more pronounced Easterly flow towards T+144. If we want to see a risk of snowfall continuing into the weekend, then it would be preferable to see the 12Z UKMO General type of evolution being closer to the final verification trend. However, even at T+144 on the 12Z ECMWF evolution, with a deep cold pool moving over the Irish Sea, there would still be rather heavy snow shower generation with significant convective possibilities.
ECMWF is really out on it's own with the majority of other model guidance showing a more pronounced Easterly flow, even beginning (continuing) at T+120. Either way, there is at least 60% confidence tonight in the continuation of these wintry conditions for another 6-7 Days, quite possibly even longer if evolutions such as GFS 12Z Operational are correct. Bitterly cold conditions will persist until next weekend, with a continuing risk of Ice Days, Severe Frosts & Snowfall.
Snowfall Risk
As many other have said on here, never underestimate the ability of the Irish Sea to support the generation of snow showers, rather heavy snow showers, given a deep cold pool being advected southwestwards.
As I was saying earlier this morning, it's going to be very difficult to pin down the exact distribution of precipitation throughout this wintry phase. Even at T+24, the evolution won't be certain & there could well be unexpected developments etc.
At the moment, after review of the UKMO 12Z Precipitation Distribution (UKMO is usually very accurate from T+0 to T+72 with regard to precipitation forecasts), the main risk zone for snowfall is generally, but by no means exclusively, an area from Louth/Dublin southwards, encompassing Eastern districts & the southeast. The western most extent of the risk at the moment appears to be West Waterford. In addition, northern coasts & northwestern areas, along with some northeastern areas are at risk of snowfall.
UKMO 12Z in particular, following it's 00Z output, does seem to suggest the potential for more organised areas of snowfall for Eastern and Southeastern areas between Tuesday and Thursday. In addition, it also suggests the risk of snowfall in Northwestern areas. Later in the week, we may well see a small feature running in from the Atlantic & slipping down the Western Seaboard, coming up against the very cold air in place which has the potential to give snowfall to these areas.
I expect all of the above mentioned areas to see, at the very least, a dusting of snow during this coming week. In this evolution, Eastern & Southeastern areas in particular are prime for snowfall. Significant accumulations are quite possible over high ground.
As stated above, UKMO 12Z looks very promising for snowfall, as does the ECMWF 12Z evolution. In fact, the latest ECMWF Operational run suggests the risk of even more than 24 Hours of rather continuous snow showers in Eastern & Southeastern areas, from later on Tuesday through to Early on Thursday.
This should not be viewed in isolation but does indicate the potential that we are looking at during this coming week:
Summary
It will remain cold to bitterly cold at times for the coming week. As a cold & unstable northeasterly airflow covers the country, there is an increasing risk of snowfall in the areas mentioned above. In addition, it is likely that several frontal features will run down across the country during the coming week, one such feature into tomorrow, offering the risk of snowfall to other areas also. Towards the end of the week, there is considerable uncertainty as to the potency of the Easterly flow. At present, the balance of favour, considering all NWP Guidance, would suggest the likelihood of at least a light to quite moderate due Easterly, perhaps slightly northeasterly flow developing. Whilst all areas will remain very to bitterly cold, the strength of the flow has significant implications in terms of snowfall potential. For example, if UKMO, GFS & GME 12Z Operationals are correct, then there will be an even higher risk of snowfall in Eastern areas. This risk is greatly reduced on ECMWF 12Z at T+120, but increasing again between T+120 and T+144.
Lots to watch in the coming days & a very interesting spell of wintry weather.
SA 0 -
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